Phasic approach to oral contraceptives.

Oral contraceptives were initially very high in estrogen and progestogen and had a uniform dosage schedule throughout the entire cycle. These early oral contraceptives were associated with high rates of side effects and complications. As a result, the hormone levels have been gradually reduced to attain the minimal amount necessary for contraception while most of the undesired side effects and complications have been eliminated. Recently, a new approach has been added. This mechanism consists of altering the dose of estrogen or progestogen or both during the month and is referred to as the phasic approach. The newest phasic pills now use a triphasic approach. Three basic formulations of the triphasic pill have been developed. In two of the three formulations, the progestogen level is altered, whereas the estrogen level remains stable; in the third formulation, both estrogen and progestogen are changed. Multiple clinical studies of the triphasics, such as ethinyl estradiol and levonorgestrel, prove that there is a significant reduction in the incidence of side effects and complications related to oral contraception.